Erick Greene

Erick Greene

Education

B.S. Dalhousie University, 1982
Ph.D. Princeton University, 1989

Research Interests

I have very broad interests in behavioural ecology, evolutionary biology and conservation biology. The organisms I study vary from birds, spiders, flies, caterpillars and plants; the topics I am interested range from behavioural ecology of communication, evolution of phenotypic plasticity, and conservation biology. Below are brief descriptions of some recent research projects.

v Alarm calling

Some persistent questions in behavioural ecology have focused on the evolution of alarm calling – why should animals produce signals that might put them at risk when they see a predator? What sort of information is being transmitted? In collaboration with Chris Templeton (www.students.washington.edu/ctemple2) and Kate Davis (Raptors of the Rockies, www.raptorsoftherockies.org) we studied the mobbing alarm calls that black-capped chickadees give in response to a wide range of perched raptors. We found that chickadees are extremely good bird-watchers. Although we cannot readily hear differences in their mobbing alarm calls, the acoustic structure of these calls varies systematically in relation to the size and threat of the predator. Recent experiments have focused on the “seet” alarm calls that many species of birds give in response to flying raptors. These alarm signals can serve as distant early warning systems: in the right conditions, a wave of information about an approaching predator can sweep through an environment at amazing speeds, and this alerts distant birds long before the raptor arrives. We also showed that red squirrels produce extremely similar alarm calls as birds in response to flying raptors.

v Song-learning, plumage and sexual selection

Lazuli buntings are a locally-common bird, and the males have delayed maturation of two important social signals: young males do not learn to sing until their first breeding season (this is much later than many song birds); and young males usually do not acquire the brilliant breeding plumage of the older males for several years. In a long-term study of individually-marked wild birds, we followed the complex social and ecological interactions that influence the development of these important acoustic and visual signals. Patterns of song learning are strongly shaped by the level of competition among males for good territories. In collaboration with Bruce Lyon (www.biology.ucsc.edu/faculty/lyon.html), we have shown that complex social interactions involving female choice, competition among males, and habitat quality results in a rare form of disruptive selection: young males with the dullest or the brightest plumage have the highest reproductive success, while young males with plumage of intermediate brightness perform poorly.

v Flies that mimic their jumping spider predators

Many flies have leg-like patterns on their wings and interesting wing-waving behaviours. Using experimental wing transplants, I showed that the flies’ wing patterns and waving behaviours mimic the aggressive displays of their jumping spider predators. This mimicry syndrome confers protection specifically against jumping spiders.

Some years ago, Noel McFarland (see his excellent 1988 book "Portraits of South Australian Geometrid Moths," Allen Press) discovered a striking developmental polyphenism, in which a geometrid caterpillar (Nemoria arizonaria) can develop to mimic either oak catkins or if it oak twigs. Subsequent rearing experiments have shown that only larval diet acts as the developmental trigger. I am currently investigating evolution of developmental reaction norms and host breadth in the genus Nemoria.

You are what you eat! These two Nemoria arizonariacaterpillars are siblings. The catkin-mimicking form on the left was reared on oak catkins, while the twig-mimicking form on the right ate oak leaves.

The genus Nemoria is large, and they range from extreme host plant specialists to broad dietary generalists. In collaboration with colleagues at Harvard University, we have started a comparative study of the group focusing on how developmental plasticity is related to host breadth. We are constructing a molecular phylogeny for the genus Nemoria throughout North and South America. This will allow us to address outstanding questions of specialization on host plants, phenotypic plasticity, and speciation in this fascinating group of caterpillars.

v Ospreys
Ospreys are unique fishing raptors, and in some places they can nest in large colonies. I tested the idea that one benefit of colonial behaviour is that it allows individuals to exchange information with each other about the location of food. By comparing the foraging behaviour and success of colonial ospreys with solitary ospreys, I was able to test this “Information Centre Hypothesis.” Indeed, colonial ospreys exchanged useful information about the distribution of patchily-distributed schooling species of fish, and this dramatically increased their foraging efficiency.

In a new study with Heiko Langner (Director of the Environmental Biogeochemistry Laboratory at The University of Montana, www.umt.edu/geosciences/faculty/langner/home.htm), Rob Domenech (Director of Raptor View Research Institute, www.raptorview.org) and local high school students, we found that ospreys in western Montana have exceedingly high levels of mercury (several orders of magnitude higher than the highest allowable levels in humans). We are starting a long-term monitoring program to identify the sources of mercury. In addition, ospreys have a predilection for lining their nests with baling twine (polypropylene rope used to tie up bales of hay). In some areas about 10-15% of osprey chicks (and some of the adults) die because they become tangled in this nylon baling twine. We are sharing this information with farmers and ranchers to reduce the amount of baling twine that is left in fields.